Help with pocket watch crystal measurement

[Blubarb]

What is the correct Ligne measurement for this pocket watch glass? I am assuming they are measured in Lignes.  I have noticed other figures and I am not sure what they refer to, eg: 25 Ligne size 25 4/16 is the 4/16 the height of the centre of the dome?

Thanks in advance. 

 

[oldhippy]

Ligne is correct. That is the right way to measure from 12 to 6 or 9 to 3. Here is a chart for you the ligne converted to mm Your measurement is a 25 ligne is 25 and 4/16 it is not the height of the dome but the diameter.

http://www.whitescrystals.com/conversion.html

and this one. http://www.jprodmanco.com/id12.html

[Blubarb]

Thank you, Oldhippy. I saw this as well and it threw me a bit as I wasn't to sure why the two numbers which I presumed were in Lignes - why 24 & 29? and why 22-24? 

[oldhippy]

The size is the size--the mic size and the bezel size are equal.

The crystal is a SIZE. People who are very familiar with size use the top number when replacing crystals.

[vinn3]

measure in inches or m.m..   the suppliers use this.  more important to know  is the oversize dimentions for a press fit or buy the factory size foe each watch.